Hazardous Waste
Of the thousands of millions of tons of waste generated in the United States annually, approximately 60 million tons are classified as hazardous. Hazardous waste is legally defined by the Resource Conservation and Recovery Act (RCRA) of 1976. The RCRA defines hazardous waste as any waste or combination of wastes, which because of its quantity, concentration, or physical,chemical, or infectious characteristics may: A) cause, or significantly contribute to, an increase in mortality or an increase in serious irreversible or incapacitating illness; or, B) pose a substantial present or potential hazard to human health or the environment when improperly treated, stored, transported, disposed of, or otherwise managed.
In the Code of Federal Regulations, the Environmental Protection Agency (EPA) specifies that a solid waste is hazardous if it meets any of four conditions: 1) It exhibits ignitability corrosivity, reactivity, or EP toxicity; 2) has been listed as a hazardous waste; 3) is a mixture containing a listed hazardous waste and a nonhazardous waste, unless the mixture is specifically excluded or no longer exhibits any of the four characteristics of hazardous waste; 4) is not specifically excluded from regulation as a hazardous waste.
The EPA established two criteria for selecting the characteristics given above. The first criterion is that the characteristic is capable of being defined in terms of physical, chemical, or other properties. The second criterion is that the properties defining the characteristic must be measurable by standardized and available test procedures. For example under the term ignitability (Hazard code label "I"), any one of four criteria can be met: 1) A liquid with a flash point less than 60°F (16°C); 2) If not a liquid, then it is capable under standard temperature and pressure of causing fire through friction, absorption of moisture, or spontaneous chemical changes, and when ignited, burns so vigorously and persistently that it creates a hazard; 3) It may be an ignitable compressed gas; 4) It is an oxidizer.
Similarly under the characteristics of corrosivity, reactivity, and toxicity, there are specifically defined requirements which are spelled out in the Code of Federal Register (CFR). Further examples are given below:
- Corrosivity (Hazard code "C") has either of the following properties: an aqueous waste with a pH equal to or less than 2.0 or greater than 12.5; or a liquid which will corrode carbon steel at a rate greater than 0.25 in (0.64 cm) per year.
- Reactivity (Hazard code "R") has at least one of the following properties: a substance which is normally unstable and undergoes violent physical and/or chemical change without being detonated; a substance which reacts violently with water (for example, sodium metal); a substance which forms a potentially explosive mixture when mixed with water; a substance which can generate harmful gases, vapors, or fumes when mixed with water; a cyanide- or sulfide-bearing waste which can generate harmful gases, vapors, or fumes when exposed to pH conditions between 2 and 12.5; a waste which, when subjected to a strong initiating source or when heated in confinement, will detonate and/or generate an explosive reaction; a substance which is readily capable of detonation at standard temperature and pressure.
- Toxicity (Hazard code "E") has the properties such that an aqueous extract contains contamination in excess of that allowed (e.g., arsenic >5 mg/l; barium 0.100 mg/l; cadmium >1 mg/l; chromium >5 mg/l; lead >5 mg/l). Additional codes under toxicity include an "acute hazardous waste" with code "H": a substance which has been found to be fatal to humans in low doses or has been found to be fatal in corresponding human concentrations in laboratory animals. Toxic waste (hazard code "T") designates wastes which have been found through laboratory studies to be a carcinogen, mutagen,or teratogen for humans or other life forms.
Certain wastes are specifically excluded from classification as hazardous wastes under RCRA, including domestic sewage, irrigation return flows, household waste, and nuclear waste. The latter is controlled via other legislation. The impetus for this effort at legislation and classification comes from several notable cases such as Love Canal, New York; Bhopal, India; Stringfellow Acid Pits (Glen Avon, California); and Seveso, Italy; which have brought media and public attention to the need for identification and classification of dangerous substances, their effects on health and the environment, and the importance of having knowledge about the potential risk associated with various wastes.
A notable feature of the legislation is its attempt at defining terms so that professionals in the field and government officials will share the same vocabulary. For example, the difference between "toxic" and "hazardous" has been established; the former denotes the capacity of a substance to produce injury and the latter denotes the probability that injury will result from the use of (or contact with) a substance.
The RCRA legislation on hazardous waste is targeted toward larger generators of hazardous waste rather than small operations. The small generator is one who generates less than 2,205 lb (1,000 kg) per month; accumulates less than 2,205 lb (1,000 kg); produces wastes which contain no more than 2.2 lb (1 kg) of acutely hazardous waste; has containers no larger than 5.3 gal (20 l) or contained in liners less than 22 lb (10 kg) of weight of acutely hazardous waste; has no greater than 220 lb (100 kg) of residue or soil contaminated from a spill, etc. The purpose of this exclusion is to enable the system of regulations to concentrate on the most egregious and sizeable of the entities that contribute to hazardous waste and thus provide the public with the maximum protection within the resources of the regulatory and legal systems.
Resources
Books
Dawson, G. W., and B. W. Mercer. Hazardous Waste Management. New York: Wiley, 1986.
Dominguez, G. S., and K. G. Bartlett. Hazardous Waste Management. Vol. 1, The Law of Toxics and Toxic Substances. Boca Raton: CRC Press, 1986.
U.S. Environmental Protection Agency. Hazardous Waste Management: A Guide to the Regulations. Washington, DC: U.S. Government Printing Office, 1980.
Wentz, C. A. Hazardous Waste Management. New York: McGraw-Hill, 1989.
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